The goal of this system is to provide a location based alarm system through which customers can broadcast their last known position in emergency situations. Imagine that you are hiking in the forest alone and don’t know how to get back to your car, or you get lost driving to your friend’s home. At times like these, how can you ask for help? With push of single button or pull off the hands free cord on this system, it will notify your friends with your latest locations immediately.
The system is divided into two parts, the client side and the server side. The client side works on the iPhone and other mobile phone platforms and is implemented in Objective C and Java ME. The server side supports more than one server while running on the Linux platform and is implemented using Java EE.
There are two problems that need to be solved before we start. First, how can we get the users’ location if their mobile phone does not have a GPS device or they are in an area without GPS signals.
As we all know, the mobile phone signal comes from the cell tower and every cell tower has a fixed cover area, The user’s approximate location can be calculated by the cell tower’s location if the tower’s location which the mobile phone gets the signal from is known.
Second, since we have more than one server running, how do we synchronize the data on different servers? If we treat this problem as another kind of server/client communication, it can easily be solved.
In this report, this system will be described based on the software development process, and how problems encountered during the system development are solved.
Source: Uppsala University
Author: Guo, Yang